Culture slides are used in biological research and in medical laboratory practice to grow or differentiate various cell and tissue cultures. These culture slides include a compartment having a single chamber or multiple discrete chambers in which the cultures may be grown. The chamber forms a reservoir which holds the mixture of cells or tissue and culture medium, while the slide forms a support surface to which the cultured cells or tissue may adhere.
As the culture process advances, progress may be monitored by viewing the cells from the bottom of the slide with the aid of an inverted microscope. When the culture has reached the desired state, the culture media is removed and the chamber is pulled from the slide and discarded, leaving the cells attached to the slide in an undisturbed state and ready for subsequent testing.
White U.S. Pat. No. 3,726,764 (the '764 patent) discloses a microbiological chamber apparatus having a box-like receptacle or compartment releasably adhered to a base member or slide. The compartment is releasably adhered to the slide using an adhesive gasket material such as the organopolysiloxane elastomer composition marketed by the General Electric Company under the designation RTV 630.
In order to adhere the compartment to the slide, the compartment base is held against the upper side of the slide using a clamping means, while an adhesive gasket material in a liquid or slurry form is injected into an injection port near the base of the compartment. The injection port is formed by a conduit located in a peripheral flange surrounding the bottom of the compartment. The internal passage of the conduit extends through the flange and into a rectangular groove formed in the bottom surface of the flange, with the rectangular groove being in general alignment with the sidewalls of the compartment. When the adhesive gasket material is injected into the injection port, the material fills the rectangular groove and contacts the slide in a pattern corresponding to the groove. The gasket material is then allowed to solidify, creating a liquid-impermeable seal between the compartment and the slide. Once the injected gasket material has solidified, the compartment is releasably adhered to the slide, and the clamping means may be removed. When the compartment is removed from the slide, the adhesive gasket remains adhered to the slide, and in combination with the upper surface of the slide, defines a well or wells upon which the cultures have grown.
Unfortunately, the microbiological chamber apparatus taught by the '764 patent has several disadvantages in use. For example, when the compartment is adhered to the slide the silicone present in the adhesive gasket material sometimes leaches onto the floor of the well on the upper surface of the slide, creating a surface which may not be conducive to growth of certain types of cell lines. The adhesive gasket material also poses some problems when the compartment is removed from the slide. As noted above, the adhesive remains adhered to the slide when the compartment is removed. Because some fixatives eat away at the gasket material, causing additional leaching and contamination of the cultures, it sometimes is desirable to remove the gasket material prior to fixing the cultures. However, removal of the gasket produces a bio-hazard. As the gasket is pulled off using forceps or the like, this removal step produces an aerosol effect, sending cell and tissue cultures up into the air. Furthermore, this cumbersome removal process takes additional lab time and may also disturb the various cultures adhering to the upper surface of the slide.
Therefore, it is desirable to have a culture slide in which the compartment may be releasably adhered and sealed to the slide without having an adhesive/sealant that leaches onto the floor of the well contaminating the cultures, or that leaves a gasket-forming sealant on the slide, which must be removed in some applications, thereby exposing the user to a bio-hazard and adding an additional step requiring additional lab time.